macOS: Add missing URI handler(#4557)

Backport from Electron Cash -- fix missing bitcoin: URI types form macOS Info.plist

contrib/build-osx/make_osx

@@ -90,5 +90,11 @@ done
 info "Building binary"
 pyinstaller --noconfirm --ascii --clean --name $VERSION contrib/build-osx/osx.spec || fail "Could not build binary"
 
+info "Adding bitcoin URI types to Info.plist"
+plutil -insert 'CFBundleURLTypes' \
+	-xml '<array><dict> <key>CFBundleURLName</key> <string>bitcoin</string> <key>CFBundleURLSchemes</key> <array><string>bitcoin</string></array> </dict></array>' \
+	-- dist/$PACKAGE.app/Contents/Info.plist \
+	|| fail "Could not add keys to Info.plist. Make sure the program 'plutil' exists and is installed."
+
 info "Creating .DMG"
 hdiutil create -fs HFS+ -volname $PACKAGE -srcfolder dist/$PACKAGE.app dist/electrum-$VERSION.dmg || fail "Could not create .DMG"